X-ray computed tomography apparatus

Abstract

An X-ray computed tomography apparatus includes an X-ray source, a high voltage generating unit, an X-ray detector detecting X-rays transmitted through a subject to generate projection data, a storage unit storing the projection data in association with electrocardiographic data of the subject, a setting unit setting a specific cardiac phase in accordance with an operator's instruction, a reconstruction unit reconstructing a tomogram based on projection data sets acquired in specific periods centered on the specific cardiac phase throughout cardiac cycles, a period extending unit extending the specific period on the basis of a heart rate fluctuation range of the subject, and a control unit controlling the high voltage generating unit to generate a relatively high dose of X-rays in the extended specific period and generate a relatively low dose of X-rays in a period other than the extended specific period.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is based upon and claims the benefit of priority from prior Japanese Patent Applications No. 2005-259614, filed Sep. 7, 2005; and No. 2005-285863, filed Sep. 30, 2005, the entire contents of both of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an X-ray computed tomography apparatus which can perform ECG gated reconstruction.[0004]2. Description of the Related Art[0005]An X-ray computed tomography apparatus provides information about a subject to be examined in the form of images on the basis of the intensities of X-rays transmitted through the subject, and serves as an important role in many medical activities such as disease diagnosis, medical treatment, and surgical operation planning.[0006]In examination of the heart which moves fast, ECG gated scanning is performed. ECG gated scanning is performed to acquire ECG gated signal...

AI Technical Summary

Benefits of technology

[0011]It is an object of the present invention to prevent the omission of part of projection data required for image reconstruction in an X-ray computed tomography apparatus which can perform ECG gated reconstruction.

Problems solved by technology

However, the actual cardiac cycle of a subject (patient) is unstable, and a cardiac cycle corresponding to several heartbeats is not constant even before scanning.

It is therefore not practical to determine an X-ray application period by using only a cardiac cycle corresponding to one heartbeat.

In examination of a fast-moving part using an X-ray computed tomography apparatus, and in particular, cardiac examination, one of the important challenges is to improve the time resolution of images.

However, arrhythmia or the like sometimes causes a situation in which projection data necessary for image reconstruction in a desired cardiac time phase has not been acquired, or projection data has not been acquired with a high S / N ratio.

In such a situation, the image quality of a reconstructed image deteriorates.

Furthermore, there is no means to check the above situation before reconstruction.

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